Copper alloys



Patented Oct. 13, 1936 UNITED STATES 2,057,368 comma ALLOYS Michael George Corson, New York, N. Y., assignor to Union Carbide and Carbon ResearchLaboratories, Inc., a corporation oi'New York No Drawing. Application April 12, 1935,

. Serial No; 16,015

3 Claims. (Cl. 75-162) The invention is a copper base alloy and a hardenable cast electrical conductor made therefrom, and an object of the invention is to provide a new and improved material suitable for 5 use as conductive parts of electrical equipment.

Pure copper has a relatively high electrical conductivity, but for many purposes it is deflcient in strength and hardness, and is diflicult to castproperly. According to the present invention, the hardness and strength of the copper is greatly increased by the addition of about 0.2% to 1% chromium, and its casting properties are improved by the addition of at least about 0.35% but less than 1% aluminum. The resulting product is highly resistant to oxidation during foundry'operations, and when molten has a high surface tension which prevents adhesion of the alloy to the sand or metal at the face of the mold.

These properties permit the'producti'on of castings the surfaces of which require little or no machining, grinding, or filling. The productis further characterized by relatively great hardness: about 80 to 85 Brinell .(500 kg. load), in the as-cast state or when air-cooled from hot working' temperatures, and about 110 Brinell when heat treated toproduce increased. precipitation hardness; and great tensile strength: about 35,000 to 55,000 pounds per square inch, depending upon the heat treatment employed. Another valuable property of the alloy is its-relatively high electrical conductivity which is, for example, over 30% of the copper standard when the alloy is in the as-cast condition. Such a high conductivity cannot be attained in any known cast copper alloy having similar strength and hardness without heat treatment. The electrical conductivity is substantially decreased if the proportion of aluminum is increased beyond the limit specified.

The content of chromium is preferably at least 0.35% of the alloy. Tin or zinc, or both, in amounts up to a total of about 0.5%, may be added without departing from the invention.

A suitable heat treatment which improves the strength and conductivity of the alloy comprises quenching it from about 700 to 900 C. and subsequently reheating it at about 400 C. to 550 C. for about 12 hours to 3 hours, the lower reheating temperature requiring the longer treatments.

Although the invention may usefully be embodied in many articles of manufacture, a pre- 'ferred embodiment is a cast electrical conductor characterized by a novel combination of high strength and high conductivity.

I claim;

1. Hardenable copper base alloy having an electrical conductivity upwards of about 30% that of pure copper, and having when molten a greater surface tension and a higher oxidation resistance than molten pure copper, which alloy contains about 0.35% to 1%. chromium and about 0.35% to 1% aluminum; the remainder of the alloy being all copper.

2. Hardenable cast electrical conductor characterized by a tensile strength of at least 35,000 pounds per square inch, a hardness of at least Brinell, and an electrical conductivity of at least 30% that of pure copper, and composed of a copper base alloy containing about 0.2% to 1% chromium, about 0.35% to about 1% aluminum, remainder all copper.

3..Copper base alloy having in the cast condition an electrical conductivity upwards of about 30% that of pure copper, a tensile strength of at least 35,000 pounds per square inch, and a hardness of at least 80 Brinell, and containing about 0. 2% to 1% chromium which imparts to the alloy the property ofhardenability by heat treatment and at least 0.35% but less than 1% aluminum which increases the surface tension and oxidation resistance of the alloy when molten, the remainder of the alloy being substantially all copper. 1

MICHAEL GEORGE CORSON. 

